Image heating apparatus for heating image formed on recording material

Abstract

An image heating apparatus for heating an image formed on a recording material includes a heating member, an excitation coil for generating a magnetic flux to induce an eddy current in the heating member, and a magnetic flux shield member coupled to the heating member for making the magnetic flux small. The magnetic flux shield width of the magnetic flux shield member in the longitudinal direction of the heating member differs in a direction intersecting with the longitudinal direction, and the magnetic flux shield member is movable in the direction intersecting with the longitudinal direction.

What is claimed is:  
     
       1. An image heating apparatus for heating an image formed on a recording material, comprising: 
       a heating member;  
       an excitation coil for generating a magnetic flux to induce an eddy current in said heating member; and  
       a magnetic flux shield member coupled to said heating member for making the magnetic flux small;  
       wherein a magnetic flux shield width of said magnetic flux shield member in a longitudinal direction of said heating member differs in a direction intersecting with the longitudinal direction, and said magnetic flux shield member is movable in the direction intersecting with the longitudinal direction.  
     
     
       2. An image heating apparatus according to  claim 1 , further comprising driving means for driving said magnetic flux shield member, and wherein said driving means moves said magnetic flux shield member in conformity with the size information of the recording material. 
     
     
       3. An image heating apparatus according to  claim 1 , wherein the magnetic flux shield width of said magnetic flux shield member in the longitudinal direction of said heating member differs gently in the direction intersecting with the longitudinal direction. 
     
     
       4. An image heating apparatus according to  claim 1 , wherein said heating member is cylindrically shaped, and said magnetic flux shield member has a shape along the shape of said heating member. 
     
     
       5. An image heating apparatus according to  claim 1 , wherein said magnetic flux shield member is disposed in an area corresponding to the longitudinal end portion of said heating member. 
     
     
       6. An image heating apparatus according to  claim 1 , wherein said magnetic flux shield member is formed of a nonmagnetic material. 
     
     
       7. An image heating apparatus according to  claim 6 , wherein said nonmagnetic material is copper, aluminum, silver or an alloy thereof. 
     
     
       8. An image heating apparatus according to  claim 6 , wherein said nonmagnetic material is ferrite.